"Hailee and Niall were going strong over the summer but split a few months ago and have been trying to keep it low-key," a source close to the actress/singer revealed. "Hailee realized she had a lot on her plate and her work schedule was insanely busy. She was gearing up for a huge press tour for her new movie," and she ultimately realized they "would be apart for mass amounts of time."

"They really tried to make it work," the insider added. "It definitely was 'young love.'"

But Steinfeld has been on the road promoting her upcoming film Bumblebee with John Cena, gearing up for its December 21 release date, and Horan recently wrapped up his Flicker world tour and is working on new music.